The invention relates to a new cathode for a cell for electrolysis, particularly of alkali chlorides, adapted to reduce overvoltage on contact with electrolyte.
In electrolysis, e.g., of alkali chlorides in an aqueous medium, it is known that, when the cathode is made of metals widely employed in industry, the potential which has to be applied to the cathode is higher in absolute value than that corresponding to the thermodynamic potential for the formation (and release) of molecular hydrogen. This difference between the potential applied and the thermodynamic potential (overvoltage) causes additional energy consumption and must, therefore, be minimized. In industrial installations allowance must further be made for the cost of the means employed and for the various economic or technical requirements in general. In the cells with solid cathodes, usually based on iron, which are used in industry particularly for electrolyzing sodium chloride, overvoltages of -200 to -300 mv. are commonly reached under industrial working conditions.
A great deal of research is knonw to have been done on electrode coatings and particularly anode coatings to reduce overvoltage, and the results of the research have been published. These include French Pat. No. 1,506,040 which describes anodes of bronze made from tungsten, titanium and various other metals. These electrodes are intended specifically for use as anodes and their chemical behavior in an alkaline medium makes them unsuitable for use in industrial electrolysis of alkali chlorides.
The present invention has now made it possible to achieve a marked reduction in cathodic overvoltage to a low value, which is relatively stable with time, without involving additional expense which would be prohibitive to the manufacturer and user.
Accordingly, it is an object of the present invention to provide a novel cathode for an electrolysis cell which will provide a reduced overvoltage when in contact with the electrolyte.
It is another object of the present invention to provide a novel cathode free from a number of disadvantages of the prior art.
Other objects will be apparent to those skilled in the art from the present description.